The former shallow, swampy, and variable-sized Giannitsa Lake or Loudias Lake (classical), south of the town, was drained in 1928-1932 by the New York Foundation Company.<ref>Eugene N. Borza, In the shadow of Olympus: the emergence of Macedon (1992) ISBN 0691008809, p. 289; Matthieu Ghilardi et al., "Human occupation and geomorphological evolution of the Thessaloniki Plain (Greece) since mid Holocene", Journal of Archaeological Science35:1:111-125 (January 2008)</ref> It or the surrounding marshland are sometimes called Borboros 'slime' or Borboros Limen.<ref>Ghilardi; Théophile Alphonse Desdevises-du-Dezert, Géographie ancienne de la Macédoine (A. Durand, 1863)</ref>

Not far from the city are the ruins of ancient Pella, birthplace and capital of Alexander the Great. Giannitsa (then called Yenije) was an important center in the Ottoman period, and several important monuments survive: the tombs of Gazi Evrenos (a 19th-century substitute for the original) and Gazi Ahmed Bey, the Great Mosque, the Army Mosque, the hammam of Evrenos, and the clocktower, which have been declared historical monuments by the Greek Archaeological Service.<ref name="hist">Vasilis Demetriades, "The Tomb of Ghāzī Evrenos Bey at Yenitsa and Its Inscription", Bulletin of the School of Oriental and African Studies (University of London) 39:2:328-332 (1976); Eleni Kanetaki, "The Still Existing Ottoman Hamams in the Greek Territory", Middle East Technical University Journal of the Faculty of Architecture21:1-2:81-110 (2005); citing M. Kiel, "Yenice-i Vardar. A forgotten Turkish cultural center in Macedonia of the 15th and 16th century", Studia Byzantina et Neohellenica Neerlandica3:300-329 (1971)</ref>

The town is home to 26,296 people (2001 census), and its attractions include the annual fair, the "Paniyiri", which runs for two weeks every September. The municipality has a population of 31,442 and a land area of 208.105 km². Other significant towns in the municipality are Ampeleiai (pop. 1,095), Melission (983), Pentaplatanon (956), and Paralimni (816).

The city was called Γενιτσά until February 1926 when its name was Hellenized.<ref>Institute for Neohellenic Research, "Name Changes of Settlements in Greece" Genitsa/Giannitsa</ref> In other languages, the city is called: Ottoman Turkish Yenice-i Vardar ('new-town of Vardar').

History

Giannitsa was inhabited since the Neolithic era. Artifacts give witness that is was inhabited in the Hellenistic era as well. In later Byzantine times, it was called Vardarion.
Around 1372, it was conquered by Gazi Evrenos. Yenije became the base of the ghazi followers of Evrenos who took Macedonia and later Albania. Yenije was an important Ottoman cultural center in the 15th and 16th centuries.<ref name=hist />

Yenije was a battleground between Bulgarian and Greek partisans in the Struggle for Macedonia. Penelope Delta's Secrets of the Swamp (referring to the shores of Giannitsa Lake) is a romanticised account of this from the Greek point of view.

Yenije "retained its emphatically Turkish character up to 1912" and members of the Evrenos family lived in Yenice in a large palace in the center of town until then. The Greek army captured Yenice after the Battle of Giannitsa in the First Balkan War (1912); part of the town was destroyed by fire.<ref>Demetriades, p. 329</ref>

After 1924, the city became thoroughly Hellenised with the exchange of the populations between Greece and Turkey and the departure of its Bulgarian inhabitants.

On 14 September1944, during the German occupation of Greece, 114 residents of Giannitsa were executed by forces of the Jagdkommando Schubert and collaborationist Greek units under the command of Georgios Poulos. Part of the city was also burned.